This invention relates to a plastic lined canal and more particularly to a canal having a plastic liner therein for the purpose of reducing leakage from the canal.
Canals, ditches, or trenches, which are here used synonymously, are widely used to transport liquids by gravity flow. There are thousands of miles of irrigation canals of various sizes in agricultural areas of the world, used to transport water to fields. Many have earthen bottoms and sides and many are lined with concrete or similar materials. Some are dug into the earth and some are dug in berms or dikes elevated above the surrounding countryside. Universally, they leak, either because they are earthen or because of cracks or other imperfections in the lining.
A wide variety of techniques have been used to lessen or control leakage from irrigation ditches and canals with more or less success. Some techniques simply dump clay or swellable materials such as bentonite into the canal on the theory that the clay particles will migrate to the source of the leak and seal off the leakage. Other techniques involve applying plastic liners to the canals, none of which have heretofore been both successful and cost effective. All techniques are costly to greater or lesser extent.
Disclosures relevant to the disclosure of this invention are found in U.S. Pat. Nos. 4,741,645; 5,213,438; 5,568,995; 5,573,351; 5,613,804; 5,735,638 and 5,882,145.
In this invention, a plastic liner is mechanically fastened to the canal in such a way that the fastener does not pass through the membrane providing leak protection. This is accomplished by providing a tab or flap on the side of the membrane adjacent the canal and passing the fastener through the tab or flap. The membrane is typically wide enough to pass up and drape over the edge of the canal. The exposed edge is terminated in a suitable permanent manner.
The membrane is preferably of a plastic material reinforced by strong fibers, preferably in a mesh. The membrane is preferably sufficiently strong that, even after being cut with an instrument, the cut cannot be enlarged by pulling on the material adjacent the cut. Preferably, the tear strength of the material is above 100 pounds of force. A preferred material is commercially available and has a tear strength of 130xc3x97110 pounds of force.
Preferably, one or more tabs or flaps on the membrane extend along the length of the trench, one near the bottom of the trench and one or more on each side. The membrane is unrolled in any suitable manner to place the tab parallel to and in the canal. In the case of a concrete lined canal, a pilot hole is drilled in the concrete and a fluted concrete nail or concrete screw is placed through a washer or suitable load spreading device, through the tab and driven into the pilot hole. In the case of an earthen canal, anchors are driven into the earth along the length of the canal and members extending down the canal are connected to the anchors. A fastener is driven through the tab and into the members.
In this manner, a durable plastic liner is mechanically connected to the canal thereby substantially reducing leakage in a cost effective manner without passing a fastener through the leak reducing membrane.
It is an object of this invention to provide an improved plastic liner for a canal.
A further object of this invention is to provide a plastic liner mechanically connected to a canal in such a manner that the fasteners do not penetrate the leak protective membrane.
These and other objects and advantages of this invention will become more apparent as this description proceeds, reference being made to the accompanying drawings and appended claims.